References: Wikipedia contributors, "Hartley transform," Wikipedia, The Free Encyclopedia, available at: http://en.wikipedia.org/w/index.php?title=Hartley_transform K. R. Castleman, Digital Image Processing. Chapter 13, p.289. Prentice. Hall, 1998. Poularikas A. D. “The Hartley Transform”. The Handbook of Formulas and Tables for Signal Processing. Ed. Alexander D. Poularikas, 1999.